Position detection device

Abstract

To provide a position detection device in which, in the linear motion direction of a rod-shaped linear moving body 50, a detection planar coil 10 is formed to be longer than the length of the linear motion range of a detection target portion 51 of the rod-shaped linear moving body 50 and is disposed so as to overlap the linear motion range, the first linear region 11 and the second linear region 12 of the detection planar coil 10 are arranged so as to be in parallel to the linear motion direction of the rod-shaped linear moving body 50, eddy currents are generated on the surface of a near-field region of the tip portion of the rod-shaped linear moving body 50 and of the near-field region of the end portion on the smaller-diameter side of a larger-diameter portion 52, although a loss occurs in the current flowing through the detection planar coil 10 due to power loss caused by the eddy currents, the position of the rod-shaped linear moving body at the time of current detection can be estimated since the magnitude of this loss is proportional to the overlap distance between the near-field region of the tip portion of the rod-shaped linear moving body 50 and the first linear region 11 and the second linear region 12 of the detection planar coil 10 in the linear motion direction of the rod-shaped linear moving body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a detection device, and more particularly to a position detection device capable of continuously detecting the position of a linear moving body formed in a rod shape and made of a magnetic material.

Background Art

[0002] In a position detection device that detects the operating state, that is, the operating position of a linear moving body formed in a rod shape and made of a magnetic material, such as a shaft, a detection coil is provided so that the linear moving body to be detected is inserted therethrough, and the position of the linear moving body is estimated by utilizing the fact that the current supplied to the coil is affected by the induced current and changes according to the operation of the linear moving body.

[0003] FIG. 12 is an explanatory diagram showing a schematic configuration of a position detection device according to the prior art. In FIG. 12, 90 is a sensor coil unit, 91 is a coil, 92 is a shaft, 93 is a sensor circuit, 94 is an ECU, 95 is a backlight, 96 is an ignition, and 97 is a non-contact position sensor.

[0004] FIG. 12 represents the invention disclosed in Japanese Patent Laid-Open No. 2000-161985. The non-contact position sensor 97 shown in FIG. 12 includes a sensor coil unit 90, a shaft 92, a sensor circuit 93, an ECU 94, a backlight 95, and an ignition 96. The coil 91 of the sensor coil unit 90 is provided in a state where a metal shaft 92 is inserted, and the shaft 92 is a linear moving body that is made to linearly move freely. Further, the sensor coil unit 90 constitutes a parallel resonance circuit with the coil 91 and a capacitor (not shown) provided inside the sensor circuit 93, and is configured to generate a high-frequency modulated magnetic field.

[0005] Also, the oscillation signal of the parallel resonance circuit of the coil 91 and the capacitor is input to a detection circuit (not shown) provided inside the sensor circuit 93. The oscillation signal input to this detection circuit changes in amplitude due to power loss caused by eddy currents when the circumferential side surface of the shaft 92 faces the inner circumferential surface of the coil 91 that generates the high-frequency modulated magnetic field. Therefore, the signal includes a change in oscillation amplitude corresponding to the linear movement of the shaft 92. The minute signal detected and output by this sensor circuit 93 has its oscillation frequency cut by a detection and amplification circuit (not shown) provided inside the sensor circuit 93, and is amplified and converted into a change in DC voltage due to the linear movement of the shaft 92. The DC current amplified and converted by the detection and amplification circuit is made into a stable DC voltage by removing the frequency range of ripples and external noise, etc. by a filter circuit (not shown) provided inside the sensor circuit 93. Further, the DC voltage signal output from the filter circuit has its impedance reduced by an output buffer circuit (not shown) provided inside the sensor circuit 93 and is output to the ECU 94. The ECU 94 discriminates the gear position of the transmission based on the voltage level of the DC voltage signal, and for example, if it is the reverse position (R), it lights up the backlight 95, and in the parking position (P) and neutral position (N), it operates so that the ignition 96 can be operated.

[0006] According to the above configuration, a sensor coil unit 90, a metal shaft 92 that is arranged to be linearly movable within a high-frequency magnetic field generated from a coil 91 of the sensor coil unit 90 and that moves in conjunction with the movement of the object to be detected, and a sensor circuit 93 that extracts the amount of change in the magnetic field that changes according to the positional relationship between the sensor coil unit 90 and the shaft 92 as a continuous signal are provided. Therefore, a signal can be continuously extracted without singularities or extreme values according to the moving distance due to the linear movement of the shaft 92. By the way, in this prior art, the coil 91 needs to be provided with the shaft 92 inserted therein. However, generally, many various components such as bearings, sleeves, link mechanisms, and sensors are arranged around a rod-shaped linear moving body such as the shaft 92. It may be difficult to provide a coil having a length corresponding to the stroke length of the rod-shaped linear moving body with the rod-shaped linear moving body inserted. That is, there are quite a few cases where a coil cannot be provided so as to cover a part of the rod-shaped linear moving body in a cylindrical shape.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] In order to solve the above problems, the present invention provides a position detection device capable of continuously detecting the position of a rod-shaped linear moving body formed of a magnetic material, the position detection device having a configuration in which a detection coil for detecting the position of the linear moving body does not need to be provided so as to cover a part of the rod-shaped linear moving body in a cylindrical shape.

Means for Solving the Problems

[0009] The invention according to claim 1 is formed by winding a coil wire in a spiral shape and in a substantially oval shape, and is provided in the vicinity of a detection target site which is any one of the tip portion of a magnetic rod-shaped linear mover that can move linearly, or the step portion between a large-diameter portion and a small-diameter portion, or the joint portion with an integrally provided insulating linear mover, and is arranged parallel to the linear movement direction of the rod-shaped linear mover. A detection planar coil, generates an alternating voltage by the inductance of the detection planar coil, detects the alternating voltage of the detection planar coil, and based on information defining the relationship between the DC voltage obtained by converting the amplitude of the alternating voltage and the position of the detection target site of the rod-shaped linear mover in the linear movement direction, it has a circuit configuration unit for calculating the position of the detection target site in the linear movement direction. The detection planar coil is formed to be longer than the length of the linear movement range of the detection target site in the linear movement direction, and is arranged so as to overlap with the linear movement range, and includes a first semi-circular region and a second semi-circular region which are both end regions, and a first linear region and a second linear region which are regions between the first semi-circular region and the second semi-circular region, and is characterized in that the first linear region and the second linear region are arranged parallel to the linear movement direction.

[0010] The invention according to claim 2 is the invention according to claim 1, wherein the detection planar coil is bent so that the first semi-circular region and the second semi-circular region face away from the rod-shaped linear mover and are orthogonal or substantially orthogonal to the linear movement direction, and the first linear region and the second linear region are longer than the length of the linear movement range of the detection target site, and is a position detection device characterized by this.

[0011] The invention according to claim 3 is the invention according to claim 2, wherein when the detection target site of the rod-shaped linear mover is the step portion between the large-diameter portion and the small-diameter portion, a magnetic shielding material is provided so as to be interposed between the detection planar coil and the small-diameter portion, and is a position detection device characterized by this.

[0012] The invention according to claim 4 is the invention according to claim 2 or claim 3, further comprising a fixed frame made of a non-magnetic material, disposed in the vicinity of the rod-shaped linear mover and parallel to the linear movement direction, and having a parallel portion to which the first linear region and the second linear region are attached; a first orthogonal portion made of a non-magnetic material, extending in a direction away from the rod-shaped linear mover from a first end portion of the parallel portion in the linear movement direction, and having the first semi-circular region attached thereto; and a second orthogonal portion made of a non-magnetic material, extending in a direction away from the rod-shaped linear mover from a second end portion of the parallel portion in the linear movement direction, and having the second semi-circular region attached thereto.

Advantages of the Invention

[0013] According to the invention described in claim 1, the first linear region and the second linear region of the coil formed such that the coil wire forms a substantially oval shape are parallel to the linear movement direction of the rod-shaped linear actuator, and the intermediate position between the first linear region and the second linear region is at the tip, the step between the large-diameter portion and the small-diameter portion, or the intermediate position of the detection target site which is any one of the joints with the integrally provided insulating linear actuator. By arranging it in this way, eddy currents are generated on the surface of the vicinity of the tip of the rod-shaped linear actuator, the vicinity of the end on the small-diameter side of the large-diameter portion, or the vicinity of the joint with the insulating linear actuator. In order to induce this eddy current, the detection planar coil generates power loss. The magnitude of this loss can be known by measuring the voltage at the end of the detection planar coil. Also, the magnitude of this loss is proportional to the size of the overlap between the first linear region and the second linear region of the detection planar coil and the vicinity of the tip of the rod-shaped linear actuator, or the vicinity of the end on the small-diameter side of the large-diameter portion, or the vicinity of the joint with the insulating linear actuator in the linear movement direction of the rod-shaped linear actuator. Therefore, the position of the rod-shaped linear actuator can be estimated from the measurement result of the voltage at the end of the detection coil. Also, it is not necessary to provide a coil so as to cover a part of the rod-shaped linear actuator in a cylindrical shape, and it is possible to mount it if a coil is provided in any region of the space around the rod-shaped linear actuator, and the restrictions on mounting are significantly reduced compared to the prior art. Also, it is not necessary to provide a coil so as to cover a part of the rod-shaped linear actuator in a cylindrical shape, and it is possible to mount it if a coil is provided in any region of the space around the rod-shaped linear actuator, and the restrictions on mounting are significantly reduced compared to the prior art.

[0014] According to the invention described in claim 2, in the first semi-circular region and the second semi-circular region of the detection planar coil, the loss of the coil accompanying the movement of the rod-shaped linear actuator does not change proportionally compared to the linear region. For this reason, it becomes difficult to estimate the relationship between the loss of the coil and the position of the rod-shaped linear actuator. Therefore, by bending the first semi-circular region and the second semi-circular region so as to face away from the rod-shaped linear actuator and be orthogonal or substantially orthogonal to the linear movement direction, the loss caused by the first semi-circular region and the second semi-circular region can be reduced to a negligible level.

[0015] According to the invention described in claim 3, when the difference in diameter between the large-diameter part and the small-diameter part of the rod-shaped linear motion body is relatively small, the power loss due to eddy current in the vicinity of the end of the small-diameter part on the large-diameter part side becomes relatively large, so it may be difficult to estimate the position of the detection target part. However, by providing a magnetic shielding material, the eddy current in the vicinity of the end of the small-diameter part on the large-diameter part side can be reduced, and the estimation of the position of the detection target part becomes easy.

[0016] According to the invention described in claim 4, the detection plane coil can be fixed near the rod-shaped linear motion body and at an appropriate distance.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0018] First, an overview of the overall configuration of the position detection device according to the first embodiment of the present invention will be described. FIG. 1 is a side view (1) showing the arrangement state of the detection planar coil according to the first embodiment of the present invention. In FIG. 1, 10 is a detection planar coil, 50 is a rod-shaped linear moving body, 51 is a detection target part, 52 is a large-diameter part, 53 is a small-diameter part, 54 is a base-end side continuous part, and 55 is a tip-end side continuous part. Further, FIG. 5 is a block diagram showing an overview of the overall configuration of the position detection device according to the first embodiment of the present invention. In FIG. 5, 40 is a position detection device, 41 is a power supply unit, 42 is a detection unit, 43 is a determination unit, 44 is a control unit, and 45 is a circuit configuration unit. In the description of each figure such as FIG. 5, the "base-end side of the rod-shaped linear moving body 50" refers to the left side of the rod-shaped linear moving body 50 in the figure, and the "tip-end side of the rod-shaped linear moving body 50" refers to the right side of the rod-shaped linear moving body 50 in the figure. Also, the "linear movement direction" indicates the direction in which the rod-shaped linear moving body 50 operates. Note that the linear movement direction coincides with the direction in which the central axis of the rod-shaped linear moving body 50 extends.

[0019] As shown in Fig. 5, the position detection device 40 according to the first embodiment of the present invention is a device for detecting the position of the rod-shaped linear mover 50 formed of a magnetic material during operation, that is, at what position within the stroke of the rod-shaped linear mover 50 it has moved at the detection time point. In the description of this embodiment, the spool provided in a hydraulic circuit or the like is used as the rod-shaped linear mover 50, but as long as it is a reciprocable rod-shaped linear mover formed of a magnetic material, a shaft or the like can also be the detection target. Specifically, the detection target part 51 is a part where portions of the rod-shaped linear mover 50 having different diameters are adjacent to each other, that is, as shown in Fig. 1, a part where a step surface between the large-diameter part 52 and the small-diameter part 53 appears, and the detection plane coil 10 is arranged in the vicinity of the detection target part 51. When a high-frequency current flows through the detection plane coil 10, eddy currents are generated on the surface of the large-diameter part 52 closest to the detection plane coil 10, so the current flowing through the detection plane coil 10 will be lost due to these eddy currents. Also, the loss due to these eddy currents is proportional to the size of the area where the large-diameter part 52 and the detection plane coil 10 face each other in the linear motion direction. That is, since the loss due to eddy currents increases in proportion to the moving distance of the rod-shaped linear mover 50 toward the tip side or the base end side, the position of the rod-shaped linear mover 50 can be detected by detecting the voltage value of the detection plane coil 10. The detection plane coil 10 is fixed to a member of the device on which the position detection device 40 is mounted. Also, when there is no appropriate member, it is fixed as shown in the position detection device according to the second embodiment of the present invention

[0020] The position detection device 40 will be described in more detail. FIG. 2 is a side view (2) showing the arrangement state of the detection planar coil according to the first embodiment of the present invention, where (a) shows the state of being located at the center of the linear movement range of the rod-shaped linear body, (b) shows the state where the rod-shaped linear body is located at the most proximal end side, and (c) shows the state where the rod-shaped linear body is located at the most distal end side. All the reference numerals used in FIG. 2 are the same as those in FIGS. 1 and 5. Further, FIG. 3 shows the detection planar coil according to the first embodiment of the present invention, where (a) is a plan view and (b) is a side view. In FIG. 3, 11 is the first linear region, 12 is the second linear region, 13 is the region used for position detection, 14 is the first semi-circular region, 15 is the second semi-circular region, and the other reference numerals are the same as those in FIG. 1. Furthermore, FIG. 4 shows the state where the detection planar coil according to the first embodiment of the present invention is bent, where (a) is a plan view and (b) is a side view. In FIG. 4, 16 is the first semi-circular region in the bent state, 17 is the second semi-circular region in the bent state, and the other reference numerals are the same as those in FIGS. 1 and 3. In addition, FIG. 11 is a graph showing the relationship between the voltage detected in the detection unit and the position of the rod-shaped linear body.

[0021] As shown in Fig. 1, the detection planar coil 10 of the position detection device 40 is disposed in the vicinity of the rod-shaped linear mover 50 that is the object to be position-detected, and is arranged so as to be parallel to the linear movement direction of the rod-shaped linear mover 50, that is, the linear movement direction. Further, as shown in Fig. 3, the detection planar coil 10 of the position detection device 40 has an overall flat oval shape. The first semi-circular region 14 and the second semi-circular region 15 near both ends of the detection planar coil 10, and the first linear region 11 and the second linear region 12 located between the first semi-circular region 14 and the second semi-circular region 15 are provided. The first linear region 11 and the second linear region 12 are linearly formed and are formed substantially parallel to each other, and are regions 13 used for position detection that generate eddy currents on the surface of the large-diameter portion 52 of the rod-shaped linear mover 50 when the detection planar coil 10 is energized. Although eddy currents are also generated on the surface of the small-diameter portion 53, since the air gap between the region 13 used for position detection and the small-diameter portion 53 is much larger than the air gap between the region 13 used for position detection and the large-diameter portion 52, it has almost no influence on position detection.

[0022] Therefore, in the detection unit 42 shown in Fig. 5 described later, when the magnitude of the loss due to eddy currents is converted into a voltage value, the output voltage value of the detection unit 42 and the moving distance of the rod-shaped linear mover 50 basically have a linear proportional relationship as shown in Fig. 11. Therefore, it is preferable that the first linear region 11 and the second linear region 12 are formed to be longer than the length of the linear movement range of the rod-shaped linear mover 50, that is, the stroke. If the lengths of the first linear region 11 and the second linear region 12 are longer than the linear movement range, the detection target portion 51 of the rod-shaped linear mover 50 moves only within the range linearly represented in Fig. 11, and the position of the detection target portion 51 can be accurately detected. Conversely, if the detection target portion 51 of the rod-shaped linear mover 50 is located outside the range where the first linear region 11 and the second linear region 12 are arranged in the linear movement direction, the output voltage value deviates from the range where the area where the large-diameter portion 52 and the detection planar coil 10 face each other is proportional to the magnitude, and it becomes difficult to accurately detect the position of the detection target portion 51.

[0023] Also, in the planar detection coil 10 shown in FIG. 1, in the linear motion direction, it is arranged such that the intermediate position between the first linear region 11 and the second linear region 12 coincides with the midpoint of the linear motion range of the detection target portion 51. When the intermediate position between the first linear region 11 and the second linear region 12 coincides with the midpoint of the linear motion range of the detection target portion 51, as shown in FIG. 2, the lengths of the first linear region 11 and the second linear region 12 can be minimized, that is, since all of the region 13 used for position detection on the proximal end side and the region 13 used for position detection on the distal end side contribute to the generation of eddy currents, the detection planar coil 10 is arranged at such a position. Also, even when it is difficult to make the intermediate position between the first linear region 11 and the second linear region 12 coincide with the midpoint of the linear motion range of the detection target portion 51, it is desirable to get as close as possible to the midpoint of the linear motion range of the rod-shaped linear moving body 50. Further, when the rod-shaped linear moving body 50 is a spool or the like, for example, there may be many portions where the diameter is different from adjacent portions, such as when there is another large-diameter portion on the proximal end side of the proximal end side continuous portion 54. Even in such a case, it is desirable to select a position where the intermediate position between the first linear region 11 and the second linear region 12 can be brought as close as possible to the midpoint of the linear motion range of the detection target portion 51 and then arrange the detection planar coil 10.

[0024] Furthermore, not only the first linear region 11 and the second linear region 12 but also the first semi-circular region 14 and the second semi-circular region 15 generate eddy currents in the same way. However, like the first linear region 11 and the second linear region 12, the region where eddy currents are generated does not change due to the movement of the rod-shaped linear mover 50, and the loss also remains the same, so it does not contribute to position detection. Therefore, it is preferable to deform the first semi-circular region 14 and the second semi-circular region 15 into the form shown in FIG. 4 instead of using them in the form shown in FIG. 3. That is, as shown in FIG. 4, the first semi-circular region 14 and the second semi-circular region 15 are bent so as to face away from the rod-shaped linear mover 50 and to be orthogonal or substantially orthogonal to the linear movement direction of the rod-shaped linear mover 50, and after being bent into the first semi-circular region 16 in the bent state and the second semi-circular region 17 in the bent state, it can be said that it is very desirable to arrange them in the vicinity of the rod-shaped linear mover 50. In the linear movement direction, for example, when the stroke length of the rod-shaped linear mover 50 is less than half of the lengths of the first linear region 11 and the second linear region 12, that is, when the stroke length of the rod-shaped linear mover 50 is considerably shorter than the lengths of the first linear region 11 and the second linear region 12, the first semi-circular region 14 and the second semi-circular region 15 may be provided without being bent.

[0025] Next, the overall configuration of the position detection device 40 will be described. The position detection device 40 includes a power supply unit 41, a detection unit 42, a determination unit 43, and a control unit 44 included in a circuit configuration unit 45 provided integrally, and a detection planar coil 10 provided separately from the circuit configuration unit 45. The power supply unit 41 forms a parallel resonance circuit by the capacitance of a capacitor installed inside and the inductance of the detection planar coil, and self-excites at this resonance frequency. The voltage generated at this time changes due to the loss caused by the eddy current induced in the rod-shaped linear body 50. This voltage is converted into a DC voltage by the detection unit and output to the determination unit 43. The determination unit 43 calculates the moving distance of the rod-shaped linear body 50 from information stored in a storage unit (not shown) and outputs it to the control unit 44. When receiving an instruction to detect the position of the rod-shaped linear body 50 from the outside or the like, the control unit 44 supplies a predetermined current to the power supply unit 41 and outputs information regarding the position of the rod-shaped linear body 50 to the control unit of the device on which the position detection device 40 (not shown) is mounted, or displays it on a display unit (not shown). Note that the circuit configuration unit 45 may be provided, for example, with the detection unit 42 and the determination unit 43 integrated, or the control unit 44 integrated with the control unit of the device on which the position detection device 40 is mounted, and is not limited to the configuration of FIG. 5.

[0026] Also, in the above description, in the rod-shaped linear mover 50 that is the object of position detection, there are a large-diameter portion 52 and a small-diameter portion 53 with a clear difference in diameter, and the portion that forms the boundary between these is described as the detection target portion 51. However, the present invention can also be applied when there is no portion corresponding to the large-diameter portion 52 and the small-diameter portion 53, or when the difference in diameter between the portions corresponding to the large-diameter portion 52 and the small-diameter portion 53 is small. FIG. 6 is a side view (3) showing the arrangement state of the detection planar coil according to the first embodiment of the present invention. (a) shows the state provided near the tip of the rod-shaped linear mover, and (b) shows the state provided at the boundary between the magnetic material portion and the non-magnetic material portion of the rod-shaped linear mover. In FIG. 6, 60 is a rod-shaped linear mover, 61 is a detection target portion, 62 is a large-diameter portion, 63 is a base-end-side small-diameter portion, 70 is a rod-shaped linear mover, 71 is a detection target portion, 72 is a magnetic portion, 73 is a non-magnetic insulator portion, 74 is a base-end-side small-diameter portion, 75 is a tip-side small-diameter portion, and the other reference numerals are the same as those in FIG. 1. Also, FIG. 7 is a side view showing a modification of the position detection device according to the first embodiment of the present invention. In FIG. 7, 30 is a magnetic shielding sheet, 56 is a rod-shaped linear mover, 57 is a detection target portion, 58 is a large-diameter portion, and the other reference numerals are the same as those in FIG. 1.

[0027] In the rod-shaped linear mover 60 shown in FIG. 6(a), the tip side of the large-diameter portion 62 is the foremost tip portion, and it shows a case where the detection planar coil 10 cannot be arranged at the boundary between the base-end-side small-diameter portion 63 and the large-diameter portion 62. In the case of the rod-shaped linear mover 60, there is no portion where eddy currents are generated on the tip side of the large-diameter portion 62. Therefore, by arranging the detection planar coil 10 with the portion of the tip-side end face of the large-diameter portion 62 as the detection target portion 61, the moving position of the rod-shaped linear mover 60 can be detected in the same manner as the rod-shaped linear mover 50. Also, in the rod-shaped linear mover 70 shown in FIG. 6(b), a magnetic portion 72 is provided at a position corresponding to the large-diameter portion 52 of the rod-shaped linear mover 50, and a non-magnetic insulator portion 73 is provided at a position corresponding to the small-diameter portion 53. Further, a magnetic base-end-side small-diameter portion 74 is provided on the base-end side of the magnetic portion 72, and a non-magnetic tip-side small-diameter portion 75 is provided on the tip side of the non-magnetic insulator portion 73. Since no eddy currents are generated in the non-magnetic insulator portion 73 and the tip-side small-diameter portion 75, by arranging the detection planar coil 10 with the tip portion of the magnetic portion 72 as the detection target portion 71, the moving position of the rod-shaped linear mover 70 can be detected in the same manner as the rod-shaped linear mover 50.

[0028] Furthermore, as shown in FIG. 7, when the difference in diameter between the large-diameter portion 58 and the small-diameter portion 59 of the rod-shaped linear mover 56 is formed to be small, eddy currents are also generated on the surface of the small-diameter portion 59. In such a case, a magnetic shielding sheet 30 is attached to the region of the small-diameter portion 59 that may face the detection planar coil 10 during operation, or to the entire outer peripheral surface of the small-diameter portion 59. By attaching the magnetic shielding sheet 30 to the small-diameter portion 59, the eddy currents generated on the surface of the small-diameter portion 59 can be reduced, and the operating position of the rod-shaped linear mover 56 can be accurately detected. If it is difficult to attach the magnetic shielding sheet 30 to the surface of the small-diameter portion 59, it may be attached to a pipe or the like provided between the detection planar coil 10 and the small-diameter portion 59. Furthermore, a plate or the like for attaching the magnetic shielding sheet 30 may be provided. As long as it is interposed between the detection planar coil 10 and the small-diameter portion 59 and can reduce the magnetic intensity reaching the small-diameter portion 59 from the detection planar coil 10, the object to which the magnetic shielding sheet 30 is attached does not matter. In addition, as long as it is a magnetic shielding material that can be arranged so as to be interposed between the detection planar coil 10 and the small-diameter portion 59, it does not have to be formed in a sheet shape.

[0029] As described above, as shown in FIGS. 1, 2, and 3, the position detection device 40 according to the first embodiment of the present invention is formed such that in the linear movement direction of the rod-shaped linear mover 50, the detection plane coil 10 is longer than the length of the linear movement range of the detection target portion 51 of the rod-shaped linear mover 50, and is arranged so as to overlap the linear movement range. The first linear region 11 and the second linear region 12 of the detection plane coil 10 are arranged parallel to the linear movement direction of the rod-shaped linear mover 50. Therefore, eddy currents are induced on the surfaces of the vicinity region of the tip of the rod-shaped linear mover 50 and the vicinity region of the end on the smaller diameter side of the large diameter portion 52, and a change occurs in the terminal voltage of the detection plane coil 10 due to the power loss resulting from these eddy currents. The magnitude of this voltage is proportional to the degree of overlap of the vicinity region of the tip of the rod-shaped linear mover 50 with respect to the first linear region 11 and the second linear region 12 of the detection plane coil 10 in the linear movement direction of the rod-shaped linear mover. Therefore, the position of the rod-shaped linear mover at the time of voltage detection can be estimated. In addition, it is not necessary to provide a coil so as to cover a part of the rod-shaped linear mover 50 in a cylindrical shape, and it can be mounted as long as a coil is provided in any region of the space around the rod-shaped linear mover. The restrictions on mounting are significantly reduced compared to the prior art.

[0030] Furthermore, as shown in FIG. 4, the first semi-circular region 14 and the second semi-circular region 15 of the planar detection coil 10 are formed in a semi-circular shape, and eddy current loss occurs regardless of the position of the rod-shaped linear mover 50. For this reason, the detection amount in the linear region 11 and the second linear region 12 will be reduced. However, the first semi-circular region 14 and the second semi-circular region 15 are bent so as to face away from the rod-shaped linear mover 50 and to be orthogonal or substantially orthogonal to the linear movement direction. Thus, the eddy current loss caused by the first semi-circular region 14 and the second semi-circular region 15 can be reduced to an extent that it can be ignored. In addition, as shown in FIG. 6(a), even when the large-diameter portion 62 of the rod-shaped linear mover 60 is the foremost end portion, the planar detection coil 10 is arranged with the portion of the front-end side end face of the large-diameter portion 62 as the detection target portion 61, whereby the moving position of the rod-shaped linear mover 60 can be detected. Furthermore, as shown in FIG. 6(b), even when the rod-shaped linear mover 70 has the magnetic portion 72 and the non-magnetic insulating portion 73 joined together, the planar detection coil 10 is arranged with the front-end portion of the magnetic portion 72 as the detection target portion 71, whereby the moving position of the rod-shaped linear mover 70 can be detected. Also, as shown in FIG. 7, even when the difference in diameter between the large-diameter portion 58 and the small-diameter portion 59 of the rod-shaped linear mover 56 is relatively small, by providing the magnetic shielding sheet 30 on the small-diameter portion 59, the eddy current in the vicinity of the end portion on the large-diameter portion 58 side of the small-diameter portion 59 can be reduced, and the estimation of the position of the detection target portion 57 becomes easy.

[0031] Next, a position detection device according to a second embodiment of the present invention will be described. FIG. 8 shows a fixed frame according to the second embodiment of the present invention, where (a) is a plan view, (b) is a side view, and (c) is a front view. In FIG. 8, 20 is a fixed frame, 21 is a parallel portion, 22 is a first orthogonal portion, 23 is a first attachment portion, 24 is a second orthogonal portion, 25 is a second attachment portion, 26 is an outer bottom surface, 27 is an outer left surface, 28 is an outer right surface, and 29a, 29b, 29c, and 29d are screw holes. Further, FIG. 9 is a side view showing a state where a detection plane coil is attached to the fixed frame according to the second embodiment of the present invention. All the reference numerals used in FIG. 9 are the same as those in FIGS. 1 and 9. Also, FIG. 10 is a side view showing a modified example of the position detection device according to the second embodiment of the present invention. In FIG. 10, 31, 32, and 33 are magnetic shielding sheets, and other reference numerals are the same as those in FIGS. 1 and 8.

[0032] The position detection device according to the second embodiment of the present invention is obtained by adding means for fixing the detection plane coil 10 at an appropriate position to the configuration of the position detection device according to the first embodiment of the present invention. As shown in FIG. 8, the fixed frame 20, which is the means for fixing, is formed of resin and includes a parallel portion 21, a first orthogonal portion 22, a first attachment portion 23, a second orthogonal portion 24, and a second attachment portion 25. The parallel portion 21, the first orthogonal portion 22, the second orthogonal portion 24, and the detection plane coil 10 are portions where the detection plane coil 10 is directly attached, and have a role of holding the detection plane coil 10 with an appropriate gap with respect to the rod-shaped linear mover 50. That is, a first linear region 11 and a second linear region 12 are attached to the outer bottom surface 26 of the parallel portion 21, a first semi-circular region 14 is attached to the outer left surface 27 of the first orthogonal portion 22, and a second semi-circular region 15 is attached to the outer right surface 28 of the second orthogonal portion 24. Also, the first attachment portion 23 and the second attachment portion 25 are for fixing the fixed frame 20 to the device on which the position detection device 40 is mounted, and are screwed using the screw holes 29a and 29b and the screw holes 29c and 29d. 26 is a first opposing surface, 27 is a thick region, 28 is a thin region, and 29 is a connecting portion.

[0033] As described above, when using the fixed frame 20, even if there is no member that can be used for fixing to the device to be implemented, the detection planar coil 10 can be fixed at an appropriate position. By the way, when a space where the fixed frame 20 can be arranged can be secured, the current flowing through the detection planar coil 10 may be affected by being directly exposed to a magnetic field generated from the power supply circuit of the device to be implemented. Therefore, it is desirable to reduce the influence of the magnetic field generated by the device on which the detection planar coil 10 is implemented. That is, as shown in FIG. 10, a magnetic shielding sheet 31 is attached to the inner surface of the bottom of the parallel portion 21, and further, a magnetic shielding sheet 32 is attached to the surface of the first semi-circular region 14 attached to the first orthogonal portion 2, and a magnetic shielding sheet 33 is attached to the surface of the second semi-circular region 15 attached to the second orthogonal portion 24, thereby reducing the influence of the magnetic field generated by the device to be implemented. When it is necessary to form the fixed frame 20 from a conductive material, the magnetic shielding sheet 31 is attached to the outer surface of the bottom of the parallel portion 21 and interposed between the parallel portion 21 and the detection planar coil 10. By interposing the magnetic shielding sheet 31 between the parallel portion 21 and the detection planar coil 10, the magnetic influence from the fixed frame 20 can be reduced.

[0034] As described above, in the position detection device according to the second embodiment of the present invention, by using the fixed frame 20, the detection planar coil 10 can be fixed near the rod-shaped linear mover and at an appropriate distance. Further, by covering the surface of the detection planar coil 10 that does not face the rod-shaped linear mover 50 with the magnetic shielding sheets 31, 32, and 33, the influence of the magnetic field generated by the device to be implemented can be reduced.

[0035] The present invention is not limited to the configurations of the embodiments described above, and can be applied to various position detection devices or position detection devices as long as it does not deviate from the scope described in each claim.

Explanation of Reference Numerals

[0036] 10 Detection planar coil 11 First linear region 12 Second linear region 13 Region used for position detection 14 First semi-circular region 15 Second semi-circular region 16 First semi-circular region in a bent state 17 Second semi-circular region in a bent state 19a Fixing hole 19b Fixing hole 19c Fixing hole 19d Fixing hole 20 Fixing frame 21 Parallel part 22 First orthogonal part 23 First attachment part 24 Second orthogonal part 25 Second attachment part 26 Outer bottom surface 27 Outer left surface 28 Outer right surface 29a Screw hole 29b Screw hole 29c Screw hole 29d Screw hole 30 Magnetic shielding sheet 31 Magnetic shielding sheet 32 Magnetic shielding sheet 33 Magnetic shielding sheet 40 Position detection device 41 Power supply part 42 Detection part 43 Judgment part 44 Control part 45 Circuit configuration part 50 Rod-shaped linear actuator 51 Detection target part 52 Large-diameter part 53 Small-diameter part 54 Base-end side continuous part 55 Tip-end side continuous part 56 Rod-shaped linear actuator 57 Detection target part 58 Large-diameter part 59 Small-diameter part 60 Rod-shaped linear actuator 61 Detection target part 62 Large-diameter part 63 Small-diameter part on the base end side 70 Rod-shaped linear mover 71 Detection target part 72 Magnetic part 73 Non-magnetic insulator part 74 Small-diameter part on the base end side 75 Small-diameter part on the tip end side 90 Sensor coil part 91 Coil 92 Shaft 93 Sensor circuit 94 ECU 95 Backlight 96 Ignition 97 Contactless position sensor

Claims

1. A detection target site, which is formed by winding a coil wire in a spiral shape and having a substantially oval shape, and is either the tip of a magnetic rod-shaped linear mover that can move linearly, or a stepped portion between a large-diameter portion and a small-diameter portion, or a joint portion with an integrally provided insulating linear mover, and a detection plane coil disposed in the vicinity of the detection target site and parallel to the linear movement direction of the rod-shaped linear mover, a circuit configuration unit that generates an alternating voltage based on the inductance of the detection plane coil, detects the alternating voltage of the detection plane coil, and calculates the position of the detection target site in the linear movement direction based on information defining the relationship between the DC voltage obtained by converting the amplitude of the alternating voltage and the position of the detection target site of the rod-shaped linear mover in the linear movement direction, wherein the detection plane coil is formed to be longer than the length of the linear movement range of the detection target site in the linear movement direction, and is disposed so as to overlap with the linear movement range, and includes a first semi-circular region and a second semi-circular region that are regions at both ends, and a first linear region and a second linear region that are regions between the first semi-circular region and the second semi-circular region, and the first linear region and the second linear region are disposed parallel to the linear movement direction. A position detection device characterized by this.

2. The detection plane coil is bent such that the first semi-circular region and the second semi-circular region face away from the rod-shaped linear mover and are orthogonal or substantially orthogonal to the linear movement direction, and the first linear region and the second linear region are longer than the length of the linear movement range of the detection target site. The position detection device according to claim 1, characterized by this.

3. When the detection target site of the rod-shaped linear mover is the stepped portion between the large-diameter portion and the small-diameter portion, a magnetic shielding material is provided so as to be interposed between the detection plane coil and the small-diameter portion. The position detection device according to claim 2, characterized by this.

4. It is made of a non-magnetic material, disposed in the vicinity of the rod-shaped linear mover and parallel to the linear movement direction, and has a parallel portion to which the first linear region and the second linear region are attached, It is made of a non-magnetic material, extends in a direction away from the rod-shaped linear mover from a first end portion of the parallel portion in the linear movement direction, and has a first orthogonal portion to which the first semi-circular region is attached, The position detection device according to claim 2 or claim 3, further comprising a fixed frame made of a non-magnetic material, extending in a direction facing away from the rod-shaped linear mover from a second end portion of the parallel portion in the linear movement direction, and having a second orthogonal portion to which the second semi-circular region is attached.

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